Some effects of bromouracil on the kinetics of thymineless death in Escherichia coli

It has been found that bromouracil is as effective as thymine for immunizing Escherichia coli 15TAU against thymineless death. It has also been found that the kinetics of thymineless death can be altered by pre-treating the cells with thymine or bromouracil in the absence of normal DNA synthesis. When bromouracil is the last base to which the cells are exposed, the cells die after a lag of 0.5 hour. When thymine is the last base, the cells die after a lag of 1.5 hours.The possible connection between these kinetics and the induction of a defective prophage is discussed.